Chapter 12 Quality Assurance External Beam Radiotherapy 2010 IAEA PDF

Chapter 12: Quality Assurance of External Beam Radiotherapy Set of 146 slides based on the chapter authored by D. I. Thwaites, B. J. Mijnheer, J. A. Mills of the IAEA publication (ISBN 92-0-107304-6): Review of Radiation Oncology Physics: A Handbook for Teachers and Students Ob...

Chapter 12: Quality Assurance of External Beam Radiotherapy Set of 146 slides based on the chapter authored by D. I. Thwaites, B. J. Mijnheer, J. A. Mills of the IAEA publication (ISBN 92-0-107304-6): Review of Radiation Oncology Physics: A Handbook for Teachers and Students Objective: To familiarize the student with the need and the concept of a quality system in radiotherapy as well as with recommended quality procedures and tests. Slide set prepared in 2006 by G.H. Hartmann (Heidelberg, DKFZ) Comments to S. Vatnitsky: [email protected] IAEA International Atomic Energy Agency CHAPTER 12. TABLE OF CONTENTS 12.1 Introduction 12.2 Managing a Quality Assurance Program 12.3 Quality Assurance Program for Equipment 12.4 Treatment Delivery 12.5 Quality Audit IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.Slide 1 12.1 INTRODUCTION 12.1.1 Definitions ❑ Commitment to Quality Assurance (QA) needs a sound familiarity with some main relevant terms such as: Quality Quality Assurance System QA in Quality Radiotherapy Control Quality Standards Definitions are given next. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 1 12.1 INTRODUCTION 12.1.1 Definitions Quality Assurance ❑ Quality Assurance is all those planned and systematic actions necessary to provide adequate confidence that a product or service will satisfy the given requirements for quality. ❑ As such QA is wide ranging, covering Procedures; Activities; Actions; Groups of staff. ❑ Management of a QA program is also called Quality System Management. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 2 12.1 INTRODUCTION 12.1.1 Definitions Quality Control ❑ Quality Control is the regulatory process through which the actual quality performance is measured, compared with existing standards, and the actions necessary to keep or regain conformance with the standards. ❑ Quality control is a part of quality system management. ❑ It is concerned with operational techniques and activities used: To check that quality requirements are met. To adjust and correct performance if the requirements are found not to have been met. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 3 12.1 INTRODUCTION 12.1.1 Definitions Quality Standards ❑ Quality standards is the set of accepted criteria against which the quality of the activity in question can be assessed. ❑ In other words: Without quality standards, quality cannot be assessed. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 4 12.1 INTRODUCTION 12.1.1 Definitions Quality System ❑ Quality System is a system consisting of: Organizational structure. Responsibilities. Procedures. Processes. Resources. required to implement a quality assurance program. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 5 12.1 INTRODUCTION 12.1.1 Definitions Quality assurance in radiotherapy ❑ Quality Assurance in Radiotherapy is all procedures that ensure consistency of the medical prescription, and safe fulfillment of that radiotherapy related prescription. ❑ Examples of prescriptions: Dose to the tumor (to the target volume). Minimal dose to normal tissue. Adequate patient monitoring aimed at determining the optimum end result of the treatment. Minimal exposure of personnel. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 6 12.1 INTRODUCTION 12.1.1 Definitions Quality standards in radiotherapy ❑ Various national or international organizations have issued recommendations for standards in radiotherapy: World Health Organization (WHO) in 1988. AAPM in 1994. European Society for Therapeutic Radiation Oncology (ESTRO) in 1995. Clinical Oncology Information Network (COIN) in 1999. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 7 12.1 INTRODUCTION 12.1.1 Definitions Quality standards in radiotherapy ❑ Other organizations have issued recommendations for certain parts of the radiotherapy process: IEC in 1989 Institute of Physics and Engineering in Medicine (IPEM) in 1999. ❑ Where recommended standards are not available, local standards need to be developed, based on a local assessment of requirements. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.1. Slide 8 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy Why does a radiotherapy center need a quality system? ❑ Next slides provide arguments to convince oneself (and others) of the need to initiate a quality project in a radiotherapy department. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.2. Slide 1 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy 1. You must establish a QA program. ❑ This follows directly from the Basic Safety Series of IAEA. Appendix II.22. says: “Registrants and licensees, in addition to applying the relevant requirements for quality assurance specified elsewhere in the Standards, shall establish a comprehensive quality assurance program for medical exposures with the participation of appropriate qualified experts in the relevant fields, such as radiophysics or radiopharmacy, taking into account the principles established by the WHO and the PAHO.” IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.2. Slide 2 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy 1. You must establish a QA program. ❑ BSS appendix II.23 says: “Quality assurance programs for medical exposures shall include: (a) Measurements of the physical parameters of the radiation generators, imaging devices and irradiation installations at the time of commissioning and periodically thereafter; (b) Verification of the appropriate physical and clinical factors used in patient diagnosis or treatment; …” IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.2. Slide 3 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy 2. It helps to provide "the best treatment“. ❑ It is a characteristic feature of the modern radiotherapy process that this process is a multi-disciplinary process. ❑ Therefore, it is extremely important that Radiation therapist cooperates with specialists in the various disciplines in a close and effective manner. Various procedures (related to the patient and that related to the technical aspects of radiotherapy) will be subjected to careful quality control. ❑ Establishment and use of a comprehensive quality system is an adequate measure to meet these requirements. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.2. Slide 4 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy 3. It provides measures to approach to the following objectives: ❑ Reduction of uncertainties and errors (in dosimetry, treatment planning, equipment performance, treatment delivery, etc.). ❑ Reduction of the likelihood of accidents and errors occurring as well as increase of the probability that they will be recognized and rectified sooner. ❑ Providing reliable inter-comparison of results among different radiotherapy centers. ❑ Full exploitation of improved technology and more complex treatments in modern radiotherapy. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.2. Slide 5 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy Reduction of uncertainties and errors...... Human errors in data transfer during the preparation and delivery of radiation treatment affecting the final result: "garbage in, garbage out" Leunens, G; Verstraete, J; Van den Bogaert, W; Van Dam, J; Dutreix, A; van der Schueren, E Department of Radiotherapy, University Hospital, St. Rafaël, Leuven, Belgium Abstract Due to the large number of steps and the number of persons involved in the preparation of a radiation treatment, the transfer of information from one step to the next is a very critical point. Errors due to inadequate transfer of information will be reflected in every next step and can seriously affect the final result of the treatment. We studied the frequency and the sources of the transfer errors. A total number of 464 new treatments has been checked over a period of 9 months (January to October 1990). Erroneous data transfer has been detected in 139/24,128 (less than 1%) of the transferred parameters; they affected 26% (119/464) of the checked treatments. Twenty-five of these deviations could have led to large geographical Radiother. Oncol. 1992: > 50 occasions of data transfer miss or important over- or underdosage (much more than 5%) of the organs in the irradiated volume, thus from one increasing the complications point to or decreasing the another tumour control forprobability, each patient! if not corrected. Such major deviations, If only of one occurring them in is 0.1% of the transferred wrong - the parameters, overall affected 5%is(25/464) outcome affected of the new treatments. The sources of these large deviations were nearly always human mistakes, whereas a considerable number of the smaller deviations were, in fact, consciously taken decisions to deviate from the IAEA intended treatment. Nearly half of the Review majorofdeviations were Physics: Radiation Oncology introduced during A Handbook input ofand for Teachers the data -in12.1.2. Students the Slide 6 check-and-confirm system, demonstrating that a system aimed to prevent accidental errors, can lead to a 12.1 INTRODUCTION 12.1.2 The need for QA in radiotherapy Full exploitation of improved technology..... ❑ Example of improved technology: Use of a multi-leaf collimator (MLC) IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.2. Slide 7 12.1 INTRODUCTION 12.1.3 Requirements on accuracy in radiotherapy ❑ Many QA procedures and tests in QA program for equipment are directly related to the clinical requirements on accuracy in radiotherapy: What accuracy is required on the absolute absorbed dose? What accuracy is required on the spatial distribution of dose (geometrical accuracy of treatment unit, patient positioning etc.)? IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.3. Slide 1 12.1 INTRODUCTION 12.1.3 Requirements on accuracy in radiotherapy ❑ Such requirements can be based on evidence from dose response curves for the tumor control probability (TCP) and normal tissue complication probability (NTCP). TCP and NTCP are usually illustrated by plotting two sigmoid Dose (Gy) curves, one for the TCP (curve A) and the other for NTCP (curve B). IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.3. Slide 2 12.1 INTRODUCTION 12.1.3 Requirements on accuracy in radiotherapy ❑ Steepness of a given TCP or NTCP curve defines the change in response expected for a given change in delivered dose. ❑ Thus uncertainties in delivered dose translate into Dose (Gy) either reductions in the TCP or increases in the NTCP, both of which worsen the clinical outcome. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.3. Slide 3 12.1 INTRODUCTION 12.1.3 Requirements on accuracy in radiotherapy ❑ ICRU Report No. 24 (1976) concludes: An uncertainty of 5 % is tolerable in the delivery of absorbed dose to the target volume. ❑ This value is generally interpreted to represent a confidence level of 1.5 – 2 times the standard deviation. ❑ Currently, the recommended accuracy of dose delivery is generally 5 % – 7 % at the 95 % confidence level. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.3. Slide 4 12.1 INTRODUCTION 12.1.3 Requirements on accuracy in radiotherapy ❑ Geometric uncertainty, for example systematic errors on the field position, block position, etc., relative to target volumes or organs at risk, also leads to dose problems: either underdosing of the required volume (decreasing the TCP) or overdosing of nearby structures (increasing the NTCP). ❑ Figures of 5 mm – 10 mm (95 % confidence level) are usually given on the tolerable geometric uncertainty. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.3. Slide 5 12.1 INTRODUCTION 12.1.4 Accidents in radiotherapy ❑ Generally speaking, treatment of a disease with radiotherapy represents a twofold risk for the patient: Firstly, and primarily, there is the potential failure to control the initial disease, which, when it is malignant, is eventually lethal to the patient; Secondly, there is the risk to normal tissue from increased exposure to radiation. ❑ Thus, in radiotherapy an accident or a misadministration is significant if it results in either an underdose or an overdose, whereas in conventional radiation protection only overdoses are generally of concern. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.4. Slide 1 12.1 INTRODUCTION 12.1.4 Accidents in radiotherapy ❑ From the general aim of an accuracy approaching 5 % (95 % confidence level), a definition for an accidental exposure can be derived: A generally accepted limit is about twice the accuracy requirement, i.e., a 10 % difference should be taken as an accidental exposure ❑ In addition, from clinical observations of outcome and of normal tissue reactions, there is good evidence that differences of 10% in dose are detectable in normal clinical practice. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.4. Slide 2 12.1 INTRODUCTION 12.1.4 Accidents in radiotherapy ❑ IAEA has analyzed a series of accidental exposures in radiotherapy to draw lessons in methods for prevention of such occurrences. ❑ Criteria for classifying them: Direct causes of mis- administrations Contributing factors Preventability of misadministration Classification of potential hazard. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.4. Slide 3 12.1 INTRODUCTION 12.1.4 Accidents in radiotherapy Examples of the direct causes of misadministrations Cause Number Cause Number Calculation error of time or dose 15 Human error during simulation 2 Inadequate review of patient chart 9 Decommissioning of teletherapy 2 source error Error in anatomical area to be 8 Error in commissioning of TPS 2 treated Error in identifying the correct patient 4 Technologist misread the 2 treatment time or MU Error involving lack of/or misuse of a 4 Malfunction of accelerator 1 wedge Error in calibration of cobalt-60 source 3 Treatment unit mechanical failure 1 Transcription error of prescribed dose 3 Accelerator software error 1 Wrong repair followed by human 1 error IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.1.4. Slide 4 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME ❑ It must be understood that the required quality system is essentially a total management system: for the total organization. for the total radiation therapy process. ❑ Total radiation therapy process includes: Clinical radiation oncology service Supportive care services (nursing, dietetic, social, etc.) All issues related to radiation treatment Radiation therapists. Physical quality assurance (QA) by physicists. Engineering maintenance. Management. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2 Slide 1 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME ❑ A number of organizations and publications have given background discussion and recommendations on the structure and management of a quality assurance program in radiotherapy or radiotherapy physics: WHO in 1988. AAPM in 1994. ESTRO in 1995 and 1998. IPEM in 1999. Van Dyk and Purdy in 1999. McKenzie et al. in 2000. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2 Slide 2 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.1 Multidisciplinary radiotherapy team ❑ One of the needs to implement a Quality System is that radiotherapy is a multidisciplinary process. ❑ Responsibilities are shared between the different disciplines and must be clearly defined. ❑ Each group has an important part in the output of the entire Radiation Oncology process, and their overall roles, Medical Physics as well as their specific quality assurance roles, are inter- Dosimetrists Radiotherapy dependent, requiring close Process cooperation. RTTs Engineering etc. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 1 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.1 Multidisciplinary radiotherapy team Multidisciplinary radiotherapy team consists of: Radiation oncologists Medical physicists Radiotherapy technologists Sometimes referred to as radiation therapist (RTT), therapy radiographer, radiation therapy technologist, radiotherapy nurse. Dosimetrists In many systems there is no separate group of dosimetrists; these functions are carried out variously by physicists, medical physics technicians or technologists, radiation dosimetry technicians or technologists, radiotherapy technologists, or therapy radiographers. Engineering technologists In some systems medical physics technicians or technologists, clinical technologists, service technicians, electronic engineers or electronic technicians. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.1. Slide 2 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ It is now widely appreciated that the concept of a Quality System in Radiotherapy is broader than a restricted definition of technical maintenance and quality control of equipment and treatment delivery. ❑ Instead, the concept should encompass a comprehensive approach to all activities in the radiotherapy department: Starting from the moment a patient enters the department until the moment he leaves it. And it should also continue into the follow-up period. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 1 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program equipment policy & knowledge & organization expertise Input Process Output Control Measure QA process control System Patient enters the Patient leaves the process seeking Control Measure department after treatment treatment QA control Outcome can be considered to be of good quality when the handling of the quality system well organizes the five aspects shown in the illustration above. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 2 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ Comprehensive quality system in radio- therapy is a management system that: Policy & organization Should be supported by the department management in order to work effectively. Must have a clear definition of its scope and of all the quality standards to be met. Must be regularly reviewed as to operation and improvement. To this end a quality assurance committee is required, which should represent all the different disciplines within radiation oncology. Must be consistent in standards for different areas of the program. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 3 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ Comprehensive quality system in radiotherapy is a management system that: Equipment Requires availability of adequate test equipment. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 4 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ Comprehensive quality system in radiotherapy is a management system that: Knowledge & expertise Requires that each staff member must have qualifications (education, training and experience) appropriate to his or her role and responsibility. Requires that each staff member must have access to appropriate opportunities for continuing education and development. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 5 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ Comprehensive quality system in radio- therapy is a management system that: Process control Requires the development of a formal written quality assurance program that details the quality assurance policies and procedures, quality control tests, frequencies, tolerances, action criteria, required records and personnel. Must be consistent in standards for different areas of the program. Must incorporate compliance with all the requirements of national legislation, accreditation, etc. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 6 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ Formal written quality assurance program is also referred to as the "Quality Manual". ❑ Quality manual has a double purpose: External Internal. ❑ Externally to collaborators in other departments, in management and in other institutions, it helps to indicate that the department is strongly concerned with quality. ❑ Internally, it provides the department with a framework for further development of quality and for improvements of existing or new procedures. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 7 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program Practical guidelines for writing your own quality manual: ESTRO Booklet 4: PRACTICAL GUIDELINES FOR THE IMPLEMENTATION OF A QUALITY SYSTEM IN RADIOTHERAPY A project of the ESTRO Quality Assurance Committee sponsored by 'Europe against Cancer' Writing party: J W H Leer, A L McKenzie, P Scalliet, D I Thwaites IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 8 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ Comprehensive quality system in radio- therapy is a management system that: QA control Requires control of the system itself, including: Responsibility for quality assurance and the quality system: quality management representatives. Document control. Procedures to ensure that the quality system is followed. Ensuring that the status of all parts of the service is clear. Reporting all non-conforming parts and taking corrective action. Recording all quality activities. Establishing regular review and audits of both the implementation of the quality system (quality system audit) and its effectiveness (quality audit). IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 9 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program ❑ When starting a quality assurance (QA) program, the setup of a QA team or QA committee is the most important first step. ❑ QA team should reflect composition of the multidisciplinary radiotherapy team. ❑ Quality assurance committee must be appointed by the department management/head of department with the authority to manage quality assurance. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 10 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program Example for the organizational structure of a radiotherapy department and the integration of a QA team Chief Executive Officer Systematic Treatment Program Radiation Treatment Program............ Management Services QA Team (Committee) Physics Radiation Oncology Radiation Therapy IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 11 12.2 MANAGING A QUALITY ASSURANCE PROGRAMME 12.2.2 Quality system/comprehensive QA program Membership and Responsibilities of the QA team (QA Committee) QA Team (Committee) Membership: Responsibilities: Radiation Oncologist(s) Patient safety Medical Physicist(s) Personnel safety Radiation Therapist(s) Dosimetry instrumentation.......... Teletherapy equipment Chair: Treatment planning Physicist or Treatment delivery Radiation Oncologist Treatment outcome Quality audit IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.2.2. Slide 12 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT ❑ The following slides are focusing on the equipment related QA program. ❑ They concentrate on the general items and systems of a QA program. ❑ Therefore, they should be "digested" in conjunction with Chapter 10 and other appropriate material concerned with each of the different categories of equipment. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT ❑ Appropriate material: Many documents are available: IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT ❑ Examples of appropriate material: AMERICAN ASSOCIATION OF PHYSICISTS IN MEDICINE (AAPM), “Comprehensive QA for radiation oncology: Report of AAPM Radiation Therapy Committee Task Group 40”, Med. Phys. 21, 581-618 (1994) INTERNATIONAL ELECTROTECHNICAL COMMISSION (IEC), “Medical electrical equipment - Medical electron accelerators-Functional performance characteristics”, IEC 976, IEC, Geneva, Switzerland (1989) INSTITUTE OF PHYSICS AND ENGINEERING IN MEDICINE (IPEM), “Physics aspects of quality control in radiotherapy”, IPEM Report 81, edited by Mayles, W.P.M., Lake, R., McKenzie, A., Macaulay, E.M., Morgan, H.M., Jordan, T.J. and Powley, S.K, IPEM, York, United Kingdom (1999) VAN DYK, J., (editor), “The Modern Technology for Radiation Oncology: A Compendium for Medical Physicists and Radiation Oncologists”, Medical Physics Publishing, Madison, Wisconsin, U.S.A. (1999) WILLIAMS, J.R., and THWAITES, D.I., (editors), “Radiotherapy Physics in Practice”, Oxford University Press, Oxford, United Kingdom (2000) IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program General structure of a quality assurance program for equipment (1) Initial specification, (2) Quality control tests acceptance testing and before the equipment is put into commissioning clinical use, quality control tests for clinical use, including should be established and a calibration where applicable formal QC program initiated (3) Additional quality control (4) Planned preventive tests maintenance program after any significant repair, in accordance with the intervention or adjustment or manufacturer’s when there is any indication of recommendations a change in performance IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program First step: Equipment specification and clinical needs assessment: ❑ In preparation for procurement of equipment, a detailed specification document must be prepared. ❑ A multidisciplinary team from the department should be involved. ❑ This should set out the essential aspects of the equipment operation, facilities, performance, service, etc., as required by the customer. ❑ Questions of which the answer is helpful to assess the clinical needs are given in the next slide. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program ❑ Questions of which the answer is helpful to assess the clinical needs: Which patients will be affected by this technology? What is the likely number of patients per year? Number of procedures or fractions per year? Will the new procedure provide cost savings over old techniques? Would it be better to refer patients to a specialist institution? Is the infrastructure available to handle the technology? Will the technology enhance the academic program? What is the organizational risk in implementation of this technology? What is the cost impact? What maintenance is required? IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Equipment specification and clinical needs assessment ❑ Once this information is compiled, the purchaser is in a good position to clearly develop his own specifications. ❑ Specification can also be based on: Manufacturers specification (brochures) Published information Discussions with other users of similar products ❑ Specification data must be expressed in measurable units. ❑ Decisions on procurement should again be made by a multi- disciplinary team. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Acceptance ❑ Acceptance of equipment is the process in which the supplier demonstrates the baseline performance of the equipment to the satisfaction of the customer. ❑ After the new equipment is installed, the equipment must be tested in order to ensure, that it meets the specifications and that the environment is free of radiation and electrical hazards to staff and patients. ❑ Essential performance required and expected from the machine should be agreed upon before acceptance of the equipment begins. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Acceptance (cont.) ❑ It is a matter of the professional judgment of the responsible medical physicist to decide whether any aspect of the agreed acceptance criteria is to be waived. ❑ This waiver should be recorded along with an agreement from the supplier, for example to correct the equipment should performance deteriorate further. ❑ Equipment can only be formally accepted to be transferred from the supplier to the customer when the responsible medical physicist either is satisfied that the performance of the machine fulfills all specifications as listed in the contract document or formally accepts any waivers. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 6 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Commissioning ❑ Commissioning is the process of preparing the equipment for clinical service. ❑ Expressed in a more quantitative way: A full characterization of its performance over the whole range of possible operation must be undertaken. ❑ In this way the baseline standards of performance are established to which all future performance and quality control tests will be referred. ❑ Commissioning includes preparation of procedures, protocols, instructions, data, etc., on the clinical use of the equipment. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 7 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Quality control ❑ It is essential that the performance of treatment equipment remain consistent within accepted tolerances throughout its clinical life ❑ Ongoing quality control program of regular performance checks must begin immediately after commissioning to test this. ❑ If these quality control measurements identify departures from expected performance, corrective actions are required. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 8 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Quality control (cont.) ❑ Equipment quality control program should specify the following: Parameters to be tested and the tests to be performed. Specific equipment to be used for that. Geometry of the tests. Frequency of the tests. Staff group or individual performing the tests, as well as the individual supervising and responsible for the standards of the tests and for actions that may be necessary if problems are identified. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 9 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program Quality control (cont.) ❑ Equipment quality control program should specify the following: Expected results. Tolerance and action levels. Actions required when the tolerance levels are exceeded. ❑ Actions required must be based on a systematic analysis of the uncertainties involved and on well defined tolerance and action levels. ❑ This procedure is explained in more detail in the following slides. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.1. Slide 10 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program If corrective actions are required: Role of uncertainty ❑ When reporting the result of a measurement, it is obligatory that some quantitative indication of the quality of the result be given. Otherwise the receiver of this information cannot really asses its reliability. ❑ Concept of uncertainty has been introduced for that. ❑ In 1993, ISO has published a Guide to the expression of uncertainty in measurement, in order to ensure that the method for evaluating and expressing uncertainty is uniform all over the world. ❑ For more details see Chapter 3. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.2. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.1 The structure of an equipment QA program If corrective actions are required: Role of tolerance level ❑ Within the tolerance level, the performance of an equipment gives acceptable accuracy in any situation. ❑ Tolerances values should be set with the aim of achieving the overall uncertainties desired. ❑ However, if the measurement uncertainty is greater than the tolerance level set, then random variations in the measurement will lead to unnecessary intervention. ❑ Therefore, it is practical to set a tolerance level at the measurement uncertainty at the 95 % confidence level. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.2. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.2 Uncertainties, tolerances and action levels If corrective actions are required: Role of action level ❑ Performance outside the action level is unacceptable and demands action to remedy the situation. ❑ It is useful to set action levels higher than tolerance levels thus providing flexibility in monitoring and adjustment. ❑ Action levels are often set at approximately twice the tolerance level. ❑ However, some critical parameters may require tolerance and action levels to be set much closer to each other or even at the same value. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.2. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.2 Uncertainties, tolerances and action levels Illustration of a possible relation between uncertainty, tolerance level and action level Tolerance level equivalent to 95% confidence interval of uncertainty standard uncertainty 4 sd 2 sd 1 sd Action level = Action level = 2 x tolerance level 2 x tolerance level Mean value IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.2. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.2 Uncertainties, tolerances and action levels System of actions: ❑ If a measurement result is within the tolerance level, no action is required. ❑ If the measurement result exceeds the action level, immediate action is necessary and the equipment must not be clinically used until the problem is corrected. ❑ If the measurement falls between tolerance and action levels, this may be considered as currently acceptable. Inspection and repair can be performed later, for example after patient irradiations. If repeated measurements remain consistently between tolerance and action levels, adjustment is required. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.2. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines ❑ A sample quality assurance program (quality control tests) for a 60Co teletherapy machine with recommended test procedures, test frequencies, and action levels is given in the following tables. ❑ Tables are structured on a daily, weekly, monthly, and annual basis. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Daily tests Procedure or item to be tested Action level Door interlock Functional Radiation room monitor Functional Audiovisual monitor Functional Lasers 2 mm Distance indicator 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Daily tests Procedure or item to be tested Action level Door interlock Functional IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Daily tests Procedure or item to be tested Action level Lasers 2 mm Distance indicator 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Weekly tests Procedure or item to be tested Action level Check of source position 3 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Monthly tests Procedure or item to be tested Action level Output constancy 2% Light/radiation field coincidence 3 mm Field size indicator 2 mm Gantry and collimator angle indicator 1º Cross-hair centering 1 mm Latching of wedges and trays Functional Emergency off Functional Wedge interlocks Functional IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 6 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Annual tests Procedure or item to be tested Action level Output constancy 2% Field size dependence of output constancy 2% Central axis dosimetry parameter constancy 2% Transmission factor constancy for all standard 2% accessories Wedge transmission factor constancy 2% Timer linearity and error 1% Output constancy versus gantry angle 2% IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 7 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Annual tests (continued) Procedure or item to be tested Action level Beam uniformity with gantry angle 3% Safety interlocks: Follow procedures of Functional manufacturer Collimator rotation isocenter 2 mm diameter Gantry rotation isocenter 2 mm diameter Table rotation isocenter 2 mm diameter Coincidence of collimator, gantry and table 2 mm diameter axis with the isocenter IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 8 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.3 QA program for cobalt-60 teletherapy machines Annual tests (cont.) Procedure or item to be tested Action level Coincidence of radiation and mechanical 2 mm diameter isocentre Table top sag 2 mm Vertical travel of table 2 mm Field light intensity Functional IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.3. Slide 9 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators ❑ Typical quality assurance procedures (quality control tests) for a dual mode linac with frequencies and action levels are given in the following tables. ❑ They are again structured according to daily, weekly, monthly, and annual tests. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Daily tests Procedure or item to be tested Action level Lasers 2 mm Distance indicator 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Daily tests Procedure or item to be tested Action level Audiovisual monitor Functional IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Daily tests Procedure or item to be tested Action level X ray output constancy 3% Electron output constancy 3% Daily output checks and verification of flatness and symmetry can be done using different multi-detector devices. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Daily tests Action Procedure or item to be tested level X ray output constancy 3% Electron output constancy 3% IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Monthly tests Procedure or item to be tested Action level X ray output constancy 2% Electron output constancy 2% Backup monitor constancy 2% X ray central axis dosimetry parameter 2% constancy (PDD, TAR, TPR) Electron central axis dosimetry 2 mm at thera- parameter constancy (PDD) peutic depth X ray beam flatness constancy 2% IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 6 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Monthly tests (continued) Procedure or item to be tested Action level Electron beam flatness constancy 3% X ray and electron symmetry 3% Emergency off switches Functional Wedge and electron cone interlocks Functional Light/radiation field coincidence 2 mm or 1 % on a side Gantry/collimator angle indicators 1º 2 mm or 2 % change in Wedge position transmission IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 7 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Monthly tests (cont.) Procedure or item to be tested Action level Tray position and applicator position 2 mm Field size indicators 2 mm Cross-hair centering 2 mm diameter Treatment table position indicators 2 mm / 1º Latching of wedges and blocking tray Functional Jaw symmetry 2 mm Field light intensity Functional IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 8 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Annual tests Procedure or item to be tested Action level X ray/electron output calibration constancy 2% Field size dependence of X ray output 2% constancy Output factor constancy for electron 2% applicators Central axis parameter constancy 2% (PDD, TAR, TPR) Off-axis factor constancy 2% Transmission factor constancy for all 2% treatment accessories IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 9 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Annual tests (cont.) Procedure or item to be tested Action level Wedge transmission factor constancy 2% Monitor chamber linearity 1% X ray output constancy with the gantry angle 2% Electron output constancy with the gantry 2% angle Off-axis factor constancy with the gantry angle 2% Arc mode Manufacturer‘s specifications IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 10 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Annual tests (cont.) Procedure or item to be tested Action level Safety interlocks functional Collimator rotation isocentre 2 mm diameter Gantry rotation isocentre 2 mm diameter Table rotation isocentre 2 mm diameter Coincidence of collimator, gantry and table 2 mm diameter axes with the isocentre Coincidence of the radiation and mechanical 2 mm diameter isocentre IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 11 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.4 QA program for linear accelerators Annual tests (cont.) Procedure or item to be tested Action level Table top sag 2 mm Vertical travel of the table 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 12 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators ❑ Treatment simulators replicate the movements of isocentric 60Coand linac treatment machines and are fitted with identical beam and distance indicators. Hence, all measurements that concern these aspects also apply to the simulator. During ‘verification session’ the treatment is set-up on the simulator exactly like it would be on the treatment unit. A verification film is taken in ‘treatment’ geometry IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators ❑ If mechanical/geometric parameters are out of tolerance on the simulator, this will affect treatments of all patients. ❑ Performance of the imaging components on the simulator is of equal importance to its satisfactory operation. ❑ Therefore, critical measurements of the imaging system are also required. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators ❑ A sample quality assurance program (quality control tests) for treatment simulators with recommended test procedures, test frequencies and action levels is given in the following tables. ❑ They are again structured according daily, monthly, and annually tests. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators Daily Tests Procedure or item to be tested Action level Safety switches Functional Door interlock Functional Lasers 2 mm Distance indicator 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators Monthly tests Procedure or item to be tested Action level Field size indicator 2 mm Gantry/collimator angle indicators 1° Cross-hair centering 2 mm diameter Focal spot-axis indicator 2 mm Fluoroscopic image quality Baseline Emergency/collision avoidance Functional Light/radiation field coincidence 2 mm or 1 % Film processor sensitometry Baseline IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators Annual tests Procedure or item to be tested Action level Collimator rotation isocenter 2 mm diameter Gantry rotation isocenter 2 mm diameter Couch rotation isocenter 2 mm diameter Coincidence of collimator, gantry, couch axes 2 mm diameter with isocenter Table top sag 2 mm Vertical travel of couch 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 6 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.5 QA program for treatment simulators Annual tests (cont.) Procedure or item to be tested Action level Exposure rate Baseline Table top exposure with fluoroscopy Baseline kVp and mAs calibration Baseline High and low contrast resolution Baseline IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.5. Slide 7 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.6 QA program for CT scanners and CT-simulation ❑ For dose prediction as part of the treatment planning process there is an increasing reliance upon CT image data with the patient in a treatment position. Gammex RMI CT test tool ❑ CT data is used for: Indication and/or data acquisition of the patient’s anatomy. To provide tissue density information which is essential for accurate dose prediction. ❑ Therefore, it is essential that the geometry and the CT densities are accurate. CT test tools are available for this purpose. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.6. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.6 QA program for CT scanners and CT-simulation ❑ A sample quality assurance program (quality control tests) for CT scanners and CT-simulation with recommended test procedures, test frequencies and action levels is given in the following tables. ❑ They are also structured on the basis of daily, monthly, and annual tests. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.6. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.6 QA program for CT scanners and CT-simulation Daily tests Procedure or item to be tested Action level Safety switches Functional Door interlock Functional Lasers 2 mm Distance indicator 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.6. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.6 QA program for CT scanners and CT-simulation Monthly tests Procedure or item to be tested Action level Field size indicator 2 mm Gantry/collimator angle indicators 1° Cross-hair centering 2 mm diameter Focal spot-axis indicator 2 mm Fluoroscopic image quality Baseline Emergency/collision avoidance Functional Light/radiation field coincidence 2 mm or 1 % Film processor sensitometry Baseline IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.6. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.6 QA program for CT scanners and CT-simulation Annual tests Procedure or item to be tested Action level Collimator rotation isocentre 2 mm diameter Gantry rotation isocentre 2 mm diameter Couch rotation isocentre 2 mm diameter Coincidence of collimator, gantry, couch axes 2 mm diameter with isocentre Table top sag 2 mm Vertical travel of couch 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.6. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems ❑ In the 1970s and 1980s treatment planning computers became readily available to individual radiation therapy centers. ❑ As computer technology evolved and became more compact so did Treatment Planning Systems (TPS), while at the same time dose calculation algorithms and image display capabilities became more sophisticated. ❑ Treatment planning computers have become readily available to virtually all radiation treatment centers. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Steps of the treatment planning process, the professionals involved in each step and the QA activities associated with these steps (IAEA TRS 430) TPS related activity IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 2 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems ❑ The middle column of the last slide summarizes the steps in the process flow of the radiation treatment planning process of cancer patients. ❑ Computerized treatment planning system, TPS, is an essential tool in this process. ❑ As an integral part of the radiotherapy process, the TPS provides a computer based: Simulation of the beam delivery set-up Optimization and prediction of the dose distributions that can be achieved both in the target volume and also in normal tissue. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 3 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems ❑ Treatment planning quality management is a subcomponent of the total quality management process. ❑ Organizationally, it involves physicists, dosimetrists, RTTs, and radiation oncologists, each at their level of participation in the radiation treatment process. ❑ Treatment planning quality management involves the development of a clear QA plan of the TPS and its use. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 4 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems ❑ Acceptance, commissioning and QC recommendations for TPS are given, for example, in AAPM Reports (TG-40 and TG-43), IPEM Reports 68 (1996) and 81 (1999), Van Dyk et al. (1993) Most recently: IAEA TRS 430 (2004) ❑ The following slides are mostly following TRS 430. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 5 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Purchase ❑ Purchase of a TPS is a major step for most radiation oncology departments. ❑ Particular attention must therefore be given to the process by which the purchasing decision is made. ❑ Specific needs of the department must be taken into consideration, as well as budget limits, during a careful search for the most cost effective TPS. ❑ The following slide contains some issues on the clinical need assessment to consider in the purchase and clinical implementation process. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 6 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Clinical need assessment: Issues Questions and/or comments Status of the existing TPS Can it be upgraded? Hardware? Software? Projected number of cases to be planned over the next Include types and complexity, for example number of 2-D 2–5 years plans without image data, number of 3-D plans with image data, complex plans, etc Special techniques Stereotactic radiosurgery? Mantle? Total body irradiation (TBI)? Electron arcs? HDR brachytherapy? Other? Number of workstations required Depends on caseload, average time per case, research and development time, number of special procedures, number of treatment planners and whether the system is also used for MU/time calculations Level of sophistication of treatment planning 3-D CRT? Participation in clinical trials? Networking capabilities? Imaging availability CT? MR? SPECT? PET? Ultrasound? CT simulation availability Network considerations Multileaf collimation available now or in the future Transfer of MLC data to therapy machines? 3-D CRT capabilities on the treatment machines Can the TPS handle the therapy machine capabilities? IMRT capabilities Available now or in the near future? Treatment trends over the next3–5 years Will there be more need for IMRT or electrons? Case load and throughput Will treatment planning become the bottleneck? IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 7 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Acceptance ❑ Acceptance testing is the process to verify that the TPS behaves according to the specifications (user’s tender document, manufacturer' specifications). ❑ Acceptance testing must be carried out before the system is used clinically and must test both the basic hardware and the system software functionality. ❑ Since during the normally short acceptance period, the user can test only basic functionality, he or she may choose a conditional acceptance and indicate in the acceptance document that the final acceptance testing will be completed as part of the commissioning process. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 8 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Acceptance RTPs Acceptance VENDOR tests USER Acceptance testing results IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 9 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Commissioning RTPs USER Commissioning Commissioning procedures results Periodic QA program IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 10 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Acceptance and Commissioning ❑ The following slides summarizes the various components of the acceptance and commissioning testing of a TPS. ❑ The intent of this information is not to provide a complete list of items that should be verified but rather is to suggest the types of issue that should be considered. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 11 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Main Issues component Hardware CPUs, memory and disk operation. Input devices: Digitizer tablet, film digitizer, imaging data (CT, MRI, ultrasound, etc.), simulator control systems or virtual simulation workstation, keyboard and mouse entry. Output: Hard copy output (plotter and/or printer), graphical display units that produce DRRs and treatment aids, unit for archiving (magnetic media, optical disk, etc.). IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 12 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Main Issues component Network Network traffic and the transfer of CT, MRI or ultrasound image integration data to the TPS. and data Positioning and dosimetric parameters communicated to the transfer treatment machine or to its record and verify system. Transfer of MLC parameter to the leaf position. Transfer of DRR information. Data transfer from the TPS to auxiliary devices (i.e., computer controlled block cutters and compensator machining devices). Data transfer between the TPS and the simulator. Data transfer to the radiation oncology management system. Data transfer of measured data from a 3-D water phantom system. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 13 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Main Issues component Software CT input. Anatomical description. 3-D objects and display. Beam description. Photon beam dose calculations: for various open fields, different SSDs, blocked fields, MLC shaped fields, inhomogeneity test cases, multi-beam plans, asymmetric jaw fields, wedged fields and others. Electron beam dose calculations: for open fields, different SSDs, shaped fields. Dose display and DVHs. Hard copy output. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 14 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Periodic quality control ❑ QA does not end once the TPS has been commissioned. ❑ It is essential that an ongoing QA program be maintained, i.e. a periodic quality control must be established. ❑ Program must be practical, and not so elaborate that it imposes an unrealistic commitment on resources and time. ❑ Two examples of a routine regular QC program (quality control tests) for a TPS are given in the next slides. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.7. Slide 15 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Frequency Procedure Tolerance level Daily Input and output devices 1 mm Monthly Checksum No change Reference subset of data 2% or 2 mm Reference prediction subset 2% or 2 mm Processor tests pass CT transfer 1 mm Annual Monitor Unit calculations 2% Reference QA test set 2 % or 2 mm IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 16 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.7 QA program for treatment planning systems Example of a periodic quality assurance program (TRS 430) Patient After Weekly Monthly Quarterly Annual specific upgrade CPU CPU Digitizer Digitizer Digitizer Hardware Plotter Plotter Backup Backup CT transfer CT transfer Anatomical CT image CT image information Anatomy Anatomy Beam Beam Beam External MU check beam Plan details Plan details software Pl. transfer Pl. transfer Pl. transfer Pl. transfer IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.4. Slide 17 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.8 QA program for test equipment ❑ Test equipment in radiotherapy concerns all the required additional equipment such as: Measurement of radiation doses. Measurement of electrical machine signals. Mechanical measurement of machine devices. ❑ Some examples of test and measuring equipment which should be considered for a quality control program are given in the next slide. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.8. Slide 1 12.3 QUALITY ASSURANCE PROGRAMME FOR EQUIPMENT 12.3.8 QA program for test equipment ❑ Local standard and field ionization chambers and electrometer. ❑ Thermometer. ❑ Barometer. ❑ Linear rulers. ❑ Phantoms. ❑ Automated beam scanning systems. ❑ Other dosimetry systems: e.g., systems for relative dosimetry (e.g., TLD, diodes, diamonds, film, etc.), in-vivo dosimetry (e.g., TLD, diodes, etc.) and for radiation protection measurements. ❑ Any other electrical equipment used for testing the running parameters of treatment equipment. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.3.8. Slide 2 12.4 TREATMENT DELIVERY 12.4.1 Patient charts ❑ Radiation chart is accompanying the patient during the entire process of radiotherapy. ❑ Basic components of a patient treatment chart: Patient name and ID. Patient photograph. Initial physical evaluation of the patient. Treatment planning data. treatment execution data. Clinical assessment during treatment. Treatment summary and follow up. QA checklist. ❑ Any errors made at the data entry of the patient chart are likely to be carried through the whole treatment. ❑ QA of the patient chart is therefore essential. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.1. Slide 1 12.4 TREATMENT DELIVERY 12.4.1 Patient charts ❑ AAPM Radiation Therapy Committee Task Group 40 recommends that: Charts be reviewed: - At least weekly. - Before the third fraction following the start or a field modification. - At the completion of treatment. Review be signed and dated by the reviewer. QA team oversee the implementation of a program which defines - Items are to be reviewed. - who is to review them. - when they are to be reviewed. - Definition of minor and major errors. - Actions to be taken, and by whom, in the event of errors. Random sample of charts be audited at intervals prescribed by the QA team. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.1. Slide 2 12.4 TREATMENT DELIVERY 12.4.1 Patient charts ❑ In particular, all planning data as well as all data entered as the interface between the planning process and the treatment delivery process should be independently checked. ❑ Examples for that are: Plan integrity. Monitor unit calculations. Irradiation parameters. ❑ Data transferred automatically, e.g., from the treatment planning system, should also be verified to check that no data corruption occurred. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.1. Slide 3 12.4 TREATMENT DELIVERY 12.4.1 Patient charts ❑ All errors that are traced during chart checking must be thoroughly investigated and evaluated by the QA team ❑ Causes should be eradicated and may result in (written) changes in the various procedures of the treatment process. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.1. Slide 4 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging ❑ As an accuracy requirement in radiotherapy, it has been stated that figures of 5 mm – 10 mm (95 % confidence level) are used as the tolerance level for the geometric uncertainty. ❑ Geometric accuracy is limited by: Uncertainties in a particular patient set-up. Uncertainties in the beam set-up. Movement of the patient or the target volume during treatment. ❑ Portal imaging is frequently applied in order to check geometric accuracy of the patient set-up with respect to the position of the radiation beam. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 1 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging ❑ Purpose of portal imaging is in particular: To verify field placement, characterized by the isocentre or another reference point, relative to anatomical structures of the patient, during the actual treatment. To verify that the beam aperture (blocks or MLC) has been properly produced and registered. Portal film device IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 2 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging Example for portal imaging: Port film Port film for a lateral irregular MLC field used in a treatment of the maxillary sinus. This method allows to visualize both the treatment field and the surrounding anatomy. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 3 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging ❑ A disadvantage of the film technique is its off-line character, which requires a certain amount of time before the result can be applied clinically. ❑ For this reason, on-line electronic portal imaging devices (EPIDs) have been developed. ❑ Three methods are clinically applied: 1. A metal plate–phosphor screen combination is used to convert the photon beam intensity into a light image. The screen is then viewed by a sensitive video camera. 2. A matrix of liquid filled ionization chambers is used. 3. A third method is based on amorphous silicon flat panel systems (see next slide). IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 4 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging Amorphous silicon type of EPID installed on the gantry of a linac. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 5 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging Comparison between digitally reconstructed radiographs (DRR) and EPID DRR treatment fields DRR EPID fields EPID images DRRs from treatment fields and large fields to verify the position of isocentre and the corresponding EPID fields. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 6 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging ❑ As part of the QA process, portal imaging may lead to various strategies for improvement of positioning accuracy such as: Improvement of patient immobilization. Introduction of correction rules. Adjustment of margins in combination with dose escalation. Incorporation of set-up uncertainties in treatment planning. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 7 12.4 TREATMENT DELIVERY 12.4.2 Portal imaging QA in portal imaging: ❑ Process control requires that local protocols must be established to specify: Who has the responsibility for verification of portal images (generally a clinician). What criteria are used as the basis to judge the acceptability of information conveyed by portal images. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.2. Slide 8 12.4 TREATMENT DELIVERY 12.4.3 In-vivo dose measurements ❑ There are many steps in the chain of processes which determine the dose delivery to a patient undergoing radiotherapy and each of these steps may introduce an uncertainty. ❑ It is therefore worthwhile, and maybe even necessary for specific patient groups or for unusual treatment conditions to use in-vivo dosimetry as an ultimate check of the actual treatment dose. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.3. Slide 1 12.4 TREATMENT DELIVERY 12.4.3 In-vivo dose measurements ❑ In-vivo dose measurements can be divided into: Intracavitary dose measurements (frequently used). Entrance dose measurements (less frequently used). Exit dose measurements (still under investigation). Diodes applied for intracavitary in-vivo dosimetry. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.3. Slide 2 12.4 TREATMENT DELIVERY 12.4.3 In-vivo dose measurements ❑ In-vivo dose measurements IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.3. Slide 3 12.4 TREATMENT DELIVERY 12.4.3 In-vivo dose measurements ❑ Examples of typical application: To check the MU calculation independently from the program used for routine dose calculations. To trace any error related to the set-up of the patient, human errors in the data transfer during the consecutive steps of the treatment preparation, unstable accelerator performance and inaccuracies in dose calculation, e.g., of the treatment planning system. To determine the intracavitary dose in readily accessible body cavities, such as the oral cavity, oesophagus, vagina, bladder, and rectum. To assess the dose to organs at risk (e.g., eye lens, gonads and lungs during TBI) or situations where the dose is difficult to predict (e.g., non- standard SSD or using bolus). IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.3. Slide 4 12.4 TREATMENT DELIVERY 12.4.3 In-vivo dose measurements Example for TLD in vivo dosimetry: Lens dose measurements 7 mm of wax bolus to mimick the position of the lens under the lid TLD detector TLD detectors lens of lens of eye eye arangement in AP or PA radiation fields arangement in lateral radiation fields IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.3. Slide 5 12.4 TREATMENT DELIVERY 12.4.4 Record-and-verify systems ❑ Computer-aided record-and-verify system aims to compare the set-up parameters with the prescribed values. IAEA Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 12.4.4. Slide 1 12.4 TREATMENT DELIVERY 12.4.4 Record-and-verify systems ❑ Patient identification data, machine parameters and dose prescription data are entered into the computer beforehand. ❑ At the time of treatment, these parameters are identified at the treatment machine and, if there is no difference, the treatment can start. ❑ If discrepancies are present this is indicated and the parameters concerned are highlighted. IAEA